Paper making



Patenta! Sep& 2& 32 I UNITED sures Want ?mam oFFc COURTLNDT B. (miturin, or LoNqmnADow, mssacnusmrs, Assenon mo cmim MANUFACTURING- COMPANY, or SOUTH munu! FALLS, MASSACHUSETTS, A con :PQBATION OF mssacnusnrrs Application file& July 7, 1930. Serial Ne. 466,152.

This invention relates to improvements in .the paper-making art and is directed more particularly to improvements in the method of and apparatus for drying a wet web of i@ .paper as it comes from the web forming apparatus.

It is common practice in paper manufacture to dry a paper web by leading it over a multip-licity of heated rigid drying drums or rolls, the web being held in contact with the drums by endless aprons or felts. This ,method has objections because the web so held against the drums is not allowed to contract as it should when drying so that in effect it is stretched or strained or at least subjected to considerable tension; For this reason, therefore, the strength of the finished paper is impaired.

Another objection to the method outlined is that the drums are necessarily heated to an extremely high temperature so that they tend to overheat'the paper. In fact the temperature in some cases is so great in order to bring about the drying that there isa tendency towards burning the paper, at least the extreme heat tends' to bring about dis-` integration whereby the quality of the paper is unfavorably affected. These hot rolls act like a hot flat iron applied to a wet fabric in that the paper is dried by vaporizing the moisture therein."

According to this invention there is pro-4 vided a novel method of and apparatus for drying a .wet web of paper wheren the web is supported by non-rigid elements for the drying operation and in such a way that it is not subjected to tension or strained in any way. In fact the web may move freely rela tive to` the supporting elements during the dryng whereby it may contractf without strain'. .As a special featureby providing non-rigid sup orting elements they may be -adapted to a sorb moisture and by being' heated moisture may be driven therefrom so 5 that as distinguished from the rior .art

method the web being dried i's nether con-' tracted with hot rigid surfaoes nor has heat applied directly thereto. This facilitates the producingof paper which has no inherent 50. strains so that itis. of greater strength than wet web of paper W as it comes from a paperthat made by present day methods-while at the same time the drying is uniform so that i the web has uniform characterists.

The numerous novel features of the invention are accomplished according to the novel method and apparatusto be hereinafte' more fully described in connection with the accompanying drawing, wherein:

making machine and Convey it around and between the heated drums. Preferably the i paper web does not contact with the drums,

but is carried between the felts so that it is relievedof strains. There may be a plurality of drums which will be heated, but they will not be heated to a drying temperature for a drying function, but rather to a lower temperature for heating the felts and thereby heating the web. I

In the manufacture of paper a suitable size such as resin is usually added to the papermaking material or stuff, while in the beaters. This size is not readly soluble in the paper-making material whereby as the web leaves the web-forming apparatus the size may be said to be crystallized and attached to the fibers instead of being disposed uniformly throughout the body of the web. It is desired according to this invention to heat the web by the .means-described sufficiently to cause the resin to flow or flux so thatit will .become more or-less uniformly distributed or dispersed throughout the body *of the web; By running the web over the heated rolls 2 between the belts it is heated sufliciently' to cause'the resin to flow, rather than for any drying function, whereby the resn Wlll be dispersed throughout the body of the web. This step of the method may be 'called a web-heating step.

Endless belts of'fabric such as 12 and 14 are provided which are supported on and driven by rolls 16 and 18. The rolls are arranged so that the belts have portions which are closely adjacent one another or are superposed on one another at places indicated at 20. These superposed portions 20 may be called runs. The web leaves the felts 4 and 6 and is received between the belts 12 and 14, whereby it is carriedlback and forth and finally discharged in a substantially dry condition as will presently appear. The belts 12 and 14 are preferably of fabrc adapted to absorb moisture and may be of some form of felt. For convenience they will be referred to as felts.

.The rolls for supporting the felts are so arranged that the runs 20 thereof are non- .parallel, that is they are preferably disposed in an angular relation to provide converging passageways therebetween while adjacent passageways converge in oppos'ite directions as shown.

In the outer and larger ends of the passageways there are located heating units indicated by 30 and air propellers in the form of electric fans 32. The units 30 are preferably in the form of resistance coils or the like while the fans are arranged to direct air over the coils. In this way warmed air is delivered inwardly towards the smaller or inner ends of the passageways. To facilitate the desired flow of warmed air through the i passageways and to withdraw moist air there is provided at the smaller ends thereof eX- haust or intake conduits 36 which are connected by piping 38 to air exhaustin or suction apparatus such as an exhaust an indicated at 40. i

It will be desirable to heat the c'oils 30 at different temperatures. For instance, the coil of a lower run may be heated to a lower temperature than a coil of an 'upper run.

This may be accomplished by providing re-V sistance current control device 31- in the circuits supplying the difierent coils as is represented in F ig. 2.

By means of the apparatus described heated air' is blown onto the felts while at the same time moist air is withdrawn' from the passageways between the felts.

This is desirable for the drying operation.

According to the novel method the felts` absorb moisture from the web and are heated as described so that they will throw ofl' moisture and thereby function efiiciently for the drying operation. In order that comparetively dry and warm felts `will be provided for receiving the paper web, heating coils such as 42 are provided past which the felts travel. These serve to dry and warm the felts so that they will be in suitable condition for receiving the web. Of course there may be any desired number and arrangement of such coils.

A plurality of rolls 44 as shown for supporting the felts may be provided below the runs theneof. 'In this way the felts need not be under too great a tension whereby the web will be loosely embraced by the felts so that it may move and contract relative thereto. These rolls may be arranged in various wa s to accomplish the purpose intended.

s will be observed the warm air for drying the felts is not delivered directly on to the web of paper, but rather on to the felts. In this way the felts are heated to dissipate moisture which is absorbed from the web. In fact the felts are heated so that they function as moisture absorbing and web drying elements. As distinguished from rigid metal drying drums the felts are yieldable and support and overlie the web so that it may move relative thereto during the drying operation. In that way the web is not strained as it is dried and the final product is uniform in its important characteristics, especially its strength.

It is desirable to enclose the apparatus within a room or enclosure so th at the drying' air is directed onto the felts and so that noist air is properly expelled. In this way proper circulation of drying air is obtained. Such an enclosure is represented by walls 46. According to the invention the apparatus will be arranged so that the suction apparatus will tend to create a partial vacuum in the enclosure which will facilitate the drying operation.

It is desirable in connection with some types of paper to subject the web to one or more surface conditioning steps. That is,

for instance, to a smoothing step whereby the surfaces of the web are smoothed out. This may be accomplished by separating the felts and then re-enters the felts. In this way the web is pressed so as to have certain desired -surface characterstcs.

As the web leaves the upper run of the felts it may in the well-known manner be led through apparatusfor applying size thereto after which the size may be dried. Preferably in the size drying operation the web will be supported by a pair of felts after the manner described so that its strength as in'the dryin operation described will not be impaire by the drying operation. V p

If desired, the web may, as it leaves the drying apparatus, be run over drying drums. Since the web is now sufliciently dried, it will be free of strains and heated drums will not tend to produce strains. Or if desired from the felts the web may be passed 'through a United States is: o

' Operations inasmuch as it has been properly dried.

Having described the novel method and mode of operation of the inventionin the form at present preferred, what I desire to claim and secure by Letters Patent of the 1. An apparatus for continuously drying a web of paper'comprising in combination, rolls spaced apart one above the other to form separate groups, which groups are spaced from one another, 'endiess felts having superposed portions extending back and forth between the rolls of said groups to form runs extending from one group to the other, the 'oups' of rolls being arranged so that ad3acent runs are in nonarallel relation forming converging passageways therebetween, means at the entrances to said passageways for directing warm air thereinto and means at the opposite ends of said passageway for withdrawin'g air therefrom, a plurality of rolls beneath said runs serving as the sole support therefor between the rolls of said groups.

` 2. An apparatus for continuusly drying a web of paper comprising in combination, rolls spaced apart one above the other to form separate groups, which groups are spaced from ing superposed portions extending back and as the :Eorth between the rolls of said groups to form runs extending from one group to the other, the groups o rolls being arranged. so

that ad acent runs are n non-parallel'relation formng converging pasageways therebetween, means at the entrances to said assageways f or directing warm air theremto and means at the opposite ends of said passageway for withdrawing air therefrom, a plurality of rolls beneath said runs serving sole support therefor between the rolls of said groups and guide rolls associated with one of said runs acting on the felts intermediate the ends of said runs for separating the felts from one another and carryin them around a pair of paper-receiving ro s ds--= posed between the felts and back again into super osed relation.

3. apparatus for drying paper comprising in combination, setsof rolls for endguide rolls for the felts of one of said runs to separate the felts from one another and carry them around a pair of paper-receiving rolls dis osed between the felts and into superpose relation again.

4. An apparatus for drying paper comprising in combination, sets of rolls for endless felts, certain of the rolls of each set being spaced one above the other to form separate groups which are spaced from one another, portions of said endless felts supported on rolls of said groups so that they have superposed ortions arranged in separated runs extendng between ,the grou s of rolls and orming pasageways there tween, other non-superposed portions of said felts being supported by other rolls of said sets and means for drying said :Eelts disposed adjacent said other non-superposed portions, guide ro'lis for the felts of one of said runs to separate the felts from one another andture. V

e COURTLANDT B. GRIFFIN.

one another, endless felts hav- -less felts, certain of the rolls of each set being spaced one above the other to, form separate groups which are spaced from one another, portions of said endless felts supported on rolls of said groups so 'that they have -superposed ortions arranged in separated runs extendng between the groups of rolls and forming passageways therebetween, other non-superposed portions 'of said felts other rolls of said' sets being supported b for drymg said felts disposed adand means jacent said other non-superposed portions, 

